Reducing unnecessary truck idling can save fuel, reduce greenhouse gas emissions, cut air pollution, and save money.

A typical long-haul combination truck that eliminates unnecessary idling could save up to 1900 gallons of fuel each

year. Saving this much fuel annually would remove 19 metric tons of carbon dioxide (a greenhouse gas), reduce NOx

and PM emissions, save nearly $3,000 in fuel costs, and lower engine maintenance costs.

What is the challenge?

Many long-haul truck drivers idle their engines during

rest periods to:

! provide heat or air conditioning for the

sleeper compartment

! keep the engine warm during cold weather

! generate electrical power for appliances 

Studies by EPA and others suggest that long-haul

combination trucks often idle up to eight hours per

day, over 300 days per year. Typical combination

trucks consume 0.8 gallons of diesel fuel during

each hour of idling, using as much as 1,900 gallons

of fuel each year per truck.

Using a heavy-duty truck engine to power cab

amenities is inefficient. It consumes fuel

unnecessarily; increases fuel costs, and causes

emissions that contribute to climate change and air

pollution. Today’s diesel engines do not need to idle

for long periods of time before and after driving.

Unnecessary engine idling also contributes to engine

wear, which increases truck maintenance costs, and

shortens engine life. 

What is the solution?

Several technological options can assist drivers in

reducing truck idling.

! Auxiliary power units (APUs) are mounted

externally on the truck cab. An APU typically

consists of a small combustion engine and

generator combination that can provide

power to the truck when the main engine is

shut off. Electricity from an APU can be used

to power heating, air conditioning, and

electrical accessories for the cab and

sleeper. 

! Automatic engine idle systems start and stop

the truck engine automatically to maintain a

specified cab temperature, or to maintain

minimum battery charge. Drivers typically

activate the system in the evening and

program a desired temperature range.

! Truck stop electrification allows trucks to use

electrical power from an external source. At

properly equipped truck stops, drivers can

shut the main truck engine off and plug into

an electrical outlet that provides power for

heaters, air conditioners, marker lights, and

other accessories. Trucks need to be

equipped with the required internal wiring,

inverter system, and HVAC system to take

advantage of truck stop electrification. 

! Advanced truck stop electrification also

provides electricity from an external source,

but doesn't require the truck to be equipped

with special systems. Truck parking bays are

installed with equipment that provides the

cab with electrical power, and heating,

cooling, and other amenities like

telecommunication hook ups, through an

external console that fits into the truck's

window frame. The truck-side console has

temperature controls, an air supply and

return pipe, a credit card reader, keypad, and

100 VAC outlet. 

The results are in . . . 

The amount of idling varies widely among trucks by

season, type of operation, and driver practices. A

typical long haul combination truck could idle up to

2,400 hours per year, which would use over 1,900

gallons of fuel. Using an APU instead of idling the

engine could reduce this fuel use by 75 percent and

eliminate over $2,000 in fuel costs plus over $300 in

engine maintenance costs each year. Truck stop

electrification can potentially eliminate all engine

idling. However, because the systems can be used

only at stations outfitted with appropriate equipment,

not all the potential savings can be obtained

immediately. Additional truck stop electrification

spaces are planned along major interstate corridors.

Next steps

Truck fleets should examine engine-operating

records to determine the percent of time spent idling

to determine potential fuel and cost-saving benefits.

Truck fleets may also check the availability of truck

stop electrification facilities along frequent routes.